Openmoko kernel ... / kernel changes affecting userspace in 2.6.27+

Andy Green andy at
Wed Oct 22 06:09:54 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:

| Sean, what do we actually need to do on this front to give Android an
| easy ride on a single kernel?  Implement the 0-255 change as Balaji has
| done or just forget about it?  If you like the change we should start
| using it.
|> I like the change, but I really would prefer peace with the other
|> developers. It essentially eliminates a bandaid change in Android (which
|> needs some rework as it assumes max 255 in several places). Doing it in
|> the kernel is much, much cleaner.

Ease of access for our customers to try Android, for which there is
widespread interest is a big win for actual users.

I cc'd devel list... in upcoming 2.6.27+ kernels, for ease of working
with Android we are changing the max_brightness in the backlight stuff
to 255 from 63.  It means that any backlight code in userspace which
does not check max_brightness needs to stop assuming that "63" is a
magic number and actually check the max_brightness thing for what full
scale looks like.

In addition, there will be considerable breakage in /sys on 2.6.27 due
to device tree changes that are aimed at fixing suspend - resume, I'll
give a list of changed paths nearer the time but be warned, hardcoded
paths in /sys are a bad idea too.

- -Andy
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